Hello. I have a made-in-Canada 1992 Ranger, 165,000km. 4WD. A.T. 2.9Lv6
Had it for about 2 years. It used to idle just fine. Start it up on a winter day the engine would hold about 1500 rpms for a bit then drop down to 700-800rpms
about 3 months ago it seems the idle began to lope. up and down and up and down and up and down 300 or 400 rpms.
I have checked for vacuum leaks by visual inspection as well as spraying while the engine was running and warmed up, starting fluid along the vacuum lines and never did detect any change in the engine's idle.
I bought at the parts store a new TPS, IAV, and ECT sensor and installed them. Maybe a tiny bit of an improvement but not really sure.
I bought a scanner and checked history engine codes and none. I cleared the codes anyway. No improvement. This truck has no EGR valve or MAP as it is Canada made.
I am at a loss now what to check next. I see on threads that this seems to be a common problem with a Ranger but I see no posts of anyone actually fixing the problem??? How can that be?
About 10,000 miles ago I did install brand new plugs, wires, dist cap and rotor, air filter, fuel filter.
I don't know where to go from here.
Help!
Thanks